Umbrellas have served many purposes for human. Some small umbrellas are light and easily carried by people and some large umbrellas are heavier and usually installed in the patio or near the beach. They can be used to shelter from the rain or sunlight. Lighted umbrellas have also been designed to provide illumination for the convenience of night activities or serving as outdoor decoration.
Lighted umbrellas powered by solar energy have become very popular in recent years because it does not require a power outlet or an extension cord to get the electrical power supply. In general, a solar power device having rechargeable batteries and solar cells are assembled on the top end of a shaft above the umbrella. Lighting devices mounted on the umbrella are powered by the solar power device. During the daytime, sun light provides the solar energy to charge the batteries for powering the lighting devices in the night.
There are a couple of shortcomings in the conventional lighted umbrella powered by solar energy. One is that the lighting devices usually take a lot of power which quickly drains out the charge in the batteries and hence the illumination only last a short period time. The other is that the lighting devices form very strong localized bright areas that are blinding to people.